Abstract

Forage rice (Oryza sativa L.) has attracted attention as a potential crop in Japan, but no optimal agricultural product system has been extensively established. The objective of this study was to determine the effects of cultivar (high-yielding indica cultivar Hokuriku 193, high-yielding indica-japonica hybrid cultivar Mizuhochikara, or standard japonica cultivar Akisayaka) and sowing pattern (broadcast or drilling) on grain yield using a new sowing machine for a well-drained paddy field. Hokuriku 193 had the highest grain yields. Hokuriku 193 and Mizuhochikara had much more spikelets than Akisayaka. Hokuriku 193 and Akisayaka had a higher percentage of filled spikelets than Mizuhochikara. At full heading, Hokuriku 193 had the highest nonstructural carbohydrate (NSC) amount. Thus, the high NSC amount of Hokuriku 193 supported a high grain yield and high percentage of filled spikelets in spite of its very many spikelets. Broadcast gave a higher rough grain yield, grain yield, and number of panicles than that of drilling, but it had no effect on the percentage of filled spikelets or the 1000-grain weight. At full heading, broadcast gave a higher NSC amount than drilling. Therefore, broadcast of high-yielding indica or indica-japonica hybrid cultivars might increase grain yield, in spite of its very high panicle number, without decreasing the percentage of filled spikelets or the 1000-grain weight by increasing the NSC amount at full heading.

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